#include <bits/stdc++.h>

using namespace std;
const int N = 110;
int dx[] = {-1, 0, 1, 0}; //上右下左
int dy[] = {0, 1, 0, -1}; //上右下左

struct Node
{
    int x, y;

}b[N];
int bl;

char a[N][N];
int n,m;
int res;

void dfs(int u,int sum){
    if(u==bl+1){
        res = max(res, sum);
        return;
    }
    dfs(u + 1, sum);

    Node c[N];
    int cl = 0;

    int cx = b[u].x, cy = b[u].y;
    for (int i = 0; i <= 4;i++){
        int tx = dx[i] + cx, ty = dy[i] + cy;
        if(tx<=0||tx>n||ty<=0||ty>m)continue;
        if (a[tx][ty] == 'C' || a[tx][ty] == 'D' || a[tx][ty] == 'Z') return;
        c[++cl] = {tx, ty};
    }
    a[cx][cy] = 'Z';
    for (int i = 1; i <= cl; i++) a[c[i].x][c[i].y] += 2;

    dfs(u + 1, sum + cl + 1);

    a[cx][cy] = 'B';
    for (int i = 1; i <= cl; i++) a[c[i].x][c[i].y] -= 2;
}
int main() {
    cin >> n >> m;
    for (int i = 1; i <= n; i++)
    for (int j = 1; j <= m; j++){
        cin >> a[i][j];
        if (a[i][j] == 'B') b[++bl] = {i, j};
    }
    dfs(1, 0);

    cout << res;
    return 0;
}